Underwater pollution control

ABSTRACT

Oil emanating from a submerged well structure which includes a wellhead and a production manifold is recovered and oil pollution of surface waters and neighboring shorelines is prevented by confining the fugitive oil underwater above an oil-water interface under a roof having side curtains and extending over the well structure. One part of the roof is fixed above the production manifold, and another part of the roof is removably secured over the wellhead and includes structure for coacting with a remotely operated running-in device for removably installing and retrieving such roof part. A fluid conduit opened by an oil-water interace-level detecting device drains oil below the roof to a production conduit of the well structure, for example, the production manifold, by gravity flow. The interface level detecting device opens the conduit when the interface reaches a predetermined minimum level below the inlet of the fluid conduit. When the interface climbs to a selected higher level below the inlet with drainage of oil into the conduit, the interface level detecting device closes the inlet valve, preventing sea water from entering the fluid conduit. Means responsive to the interface level shut in production from the well structure if confined oil accumulates to a predetermined maximum interface level below the inlet of the fluid conduit. Attainment of the predetermined minimum level, as indicated by the interface level detector device, may actuate electrical circuitry provided for connection to an indicator placed at a remote accessible location, signaling the occurrence of oil leakage from the submerged well structure and the accumulation of the predetermined minimum volume of fugitive oil. The fluid conduit may have valve means to prevent backflow of oil into the confining area from the well structure production conduit. Valve means may regulate the discharge of oil into the well structure from the fluid conduit. Pumping means may be utilized to force oil from the fluid conduit into the well structure when the production line pressure in the well structure exceeds the hydrostatic pressure at the level of the well structure.

United States Patent Childers 51 June 20, 1972 [54] UNDERWATER POLLUTIONCONTROL [72] Inventor: Thomas W. Childers, Woodland Hills,

Calif.

[73] Assignee: Esso Production Research Company,

Houston, Tex.

[22] Filed: Jan. 2, 1970 211 App]. No.: 174

52 u.s.c| ..l66/.5,61/1 F 2,104,660 1/1938 Long et al.... 166/542,783,970 3/1957 Gillespie 166/.5 X 3,063,500 1 1/1962 Logan 166/.53,389,559 6/1968 Logan... .....6l/l 3,454,083 7/1969 Brooks. ..166/.53,461,957 8/1969 West ..l66/.5

Primary Examiner-Marvin A. Champion Assistant Examiner-Richard E.Favreau Attorney-Thomas B. McCulloch, Melvin F. Fincke, John S.Schneider, Sylvester W. Brock, Jr. and Timothy L. Burgess [57] ABSTRACTOil emanating from a submerged well structure which includes a wellheadand a production manifold is recovered and oil pollution of surfacewaters and neighboring shorelines is prevented by confining the fugitiveoil underwater above an oil-water interface under a roof having sidecurtains and extending over the well structure. One part of the roof isfixed above the production manifold, and another part of the roof isremovably secured over the wellhead and includes structure for coactingwith a remotely operated running-in device for removably installing andretrieving such roof part. A fluid conduit opened by an oil-waterinterace-level detecting device drains oil below the roof to aproduction conduit of the well structure, for example, the productionmanifold, by gravity flow. The interface level detecting device opensthe conduit when the interface reaches a predetermined minimum levelbelow the inlet of the fluid conduit. When the interface climbs to aselected higher level below the inlet with drainage of oil into theconduit, the interface level detecting device closes the inlet valve,preventing sea water from entering the fluid conduit. Means responsiveto the interface level shut in production from the well structure ifconfined oil accumulates to a predetermined maximum interface levelbelow the inlet of the fluid conduit. Attainment of the predeterminedminimum level, as indicated by the interface level detector device, mayactuate electrical circuitry provided for connection to an indicatorplaced at a remote accessible location, signaling the occurrence of oilleakage from the submerged well structure and the accumulation of thepredetermined minimum volume of fugitive oil. The fluid conduit may havevalve means to prevent backflow of oil into the confining area from thewell structure production conduit. Valve means may regulate thedischarge of oil into the well structure from the fluid conduit. Pumpingmeans may be utilized to force oil from the fluid conduit into the wellstructure when the production line pressure in the well structureexceeds the hydrostatic pressure at the level of the well structure.

28 Claims, 18 Drawing Figures Y PATENTEDJUHZOIBYZ 3,670,814

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UNDERWATER POLLUTION CONTROL BACKGROUND OF THE INVENTION l. Field of theInvention The present invention relates to underwater well structures,and more particularly, to underwater pollution control and apparatustherefor to be extended over such well structures.

2. Description of the Prior Art If oil produced from offshore strataescapes subsea well production facilities and rises to form oil slickson surface waters, it may pollute not only those waters but neighboringshorelines. Avoidance of this condition is imperative, yet leakage fromsubmerged production equipment may not be detected until an oil slickappears on the surface of the sea. Minor but continuing leaks ofproduction equipment may not produce a noticeable surface slick, andlarge amounts of production may be lost as time passes.

SUMMARY OF THE INVENTION In view of the above problems associated withthe subsea production of oil, it is an object of the invention toprovide for the capture and confinement underwater of oil escaping intothe sea from one or more'submerged well structures, thereby preventingoil pollution of surface waters and neighboring shorelines.

Another object of the invention is to provide for the early detection ofoil emanating from one or more submerged well structures.

A further object of the invention it to provide for the accumulation andlocal recovery, free of sea water, of oil which has escaped from one ormore of submerged well structures.

Still another object of the invention is to provide for the shutting inof production from a loss of oil from a submerged well structure.

These objects are achieved in the present invention by provision ofapparatus extending over a submerged well structure for confiningfugitive oil from said well structure underwater above an oil-waterinterface with the further provision of apparatus responsive to thelevel of that interface for shutting in production from that wellstructure when that interface is at a predetermined maximum volumewithin the confining means; by the additional provision of apparatus forremoving oil from its confinement above the oil-water interface when apredetermined minimum of oil has accumulated and for discharging thatoil back into the well structure; and by the further provision of meansfor electrical connection to an indicator at a remote accessiblelocation for actuating that indicator when the predetermined minimum ofoil has accumulated, signaling a remote accessible location that thewell structure is losing oil.

This invention possesses many other advantages, and has other objects inaddition to the objects already described, all of which may be made moreclearly apparent from a specific consideration of preferred forms inwhich the invention may be embodied. These forms are shown in thedrawings described below which accompany and form part of the presentspecification. These forms are then described in detail for the purposeof illustrating the general principles of the invention; it is to beunderstood, however, that the detailed description of the preferredembodiments is not to be taken in a limiting sense, since the scope ofthe invention is best defined by the appended claims.

DESCRIPTION OF THE DRAWINGS taken along the lines 3-3 submerged wells inthe event of FIG. 4 illustrates the installation of a plurality ofunderwater pollution control apparatuses for a plurality of subseawells;

FIG. 5 is an enlarged isometric view of an oil removal line inlet valveof the apparatus of FIG. 2;

FIG. 6 is an alternative arrangement for oil removal lines of theapparatus of FIGS. 1 and 2;

FIG. 7 is a pump arrangement for use in connection with oil retrievalfrom the apparatus of FIG. 1 and 12;

FIG. 8 illustrates the installation of a portion of the underwaterpollution control apparatus, shown in longitudinal section;

FIG. 9 is a rear elevational view taken along the lines 9-9 of FIG. 8;

FIG. 10 is an enlarged longitudinal section of the running-in toolillustrated in FIG. 8;

FIG. 11 is a top elevational view taken along the lines 1 1- 1 l of FIG.10;

FIG. 12 is a longitudinal sectional and side elevational view depictingthe installation of a portion of the underwater pollution controlapparatus for opposed submerged well structures;

FIGS. 13(a)-(c) illustrate another method of installing a portion of thepollution control apparatus;

FIG. 14 is a cross sectional view taken along the lines 14- 14 of FIG.7(a);

FIG. 15 is an enlarged side elevational view of a portion of thepollution control apparatus illustrated in FIGS. 13(a )-(c); and

FIG. 16 is an elevational view to the rear taken along the lines 16--16of FIG. 12.

DESCRIPTION OF THE PREFERRED EMBODIMENTS An underwater pollution controldevice A is illustrated in the drawings (see especially FIGS. 1 and 2)which is adapted to be installed over a submerged well structure B. Thesubmerged well structure 8 includes a wellhead 10, which surmounts awell 11 illustrated as a dual completion well; production lines 12, 13,which produce dual completion well 11; and production manifolds 14, 15,into which production from production lines 12, 13 feeds by way ofjumper pipes 16, 17. Production manifolds 14, 15 connect into pipelineswhich lead to storage tanks which may be submerged, located above theocean's surface on a fixed or floating platform, or onshore. Productionthrough production lines 12, 13 is regulated by production controlvalves 18, 19, and feed through production manifolds 14, 15 is regulatedby production manifold valves 20, 21. Production control valves 18, 19and production manifold valves 20, 21 are linked by hydraulic lines(e.g. lines 22, 23) to an electro-hydraulic production control module24, which transmits and receives monitoring and control signals,respectively, to and from a remote accessible site, such as a fixed orfloating platfonn or an onshore station, by means of a multi-oonductorsignal power cable 25. The submerged well structure and its amociatedproduction control equipment are supported on ocean floor 26 by means ofa template structure 27, which includes a base 28 mounting front andrear guideposts 29a and 29b, respectively, from which guide wires 30 areextended to a fixed or floating platform on the ocean: surface.

The underwater pollution control device A includes a roof 31 extendingover the well structure B. Referring particularly to FIGS. 1 and 2, roof31 takes the form of an inverted pan, with a top surface 32 and sidecurtains 33, and includes a portion 34 over the manifold and a portion35 over the wellhead. The manifold cover pan 34 is aflixed overproduction manifold: 14, 15, suitably by structural members 36 securedto the header portion 37 of the uppermost manifold 14. Wellhead coverpan 35 is removably secured above wellhead 10 by structure hereinafterdescribed coacting with the guideposts 29a and 29b of the template 27,in order that the wellhead cover pan 35 may be removed for verticalre-entry to perform work-over operations and the like.

Roof 31 may take several attitudes. In the embodiment illustrated inFIG. 1, roof 31 has a sloped configuration over wellhead structure B,the roof ascending from the portion 35 covering the wellhead to theportion 34 covering the manifold. The forward portion 38 of the wellheadcover pan 35 is inserted under the rear portion 39 of the manifold coverpan 34 to form a continuous and upwardly inclining passage from wellheadcover pan 35 to manifold cover pan 34 by which oil fluids, of lighterspecific gravity than water, and fugitive from well structure B, aredirected to flow by gravity upward under manifold cover pan 34. Manifoldcover pan 34 includes as oil fluid collecting structure a transversepassage 40 provided by a gutter 41 formed in the forward portion ofmanifold cover pan 34. As illustrated in FIG. 3, gutter 41 convergesfrom side curtains 33 of manifold cover pan 34 to drain into a standpipe42 which empties into a roof receiving chamber 43. For a multi-wellheadtemplate, one manifold cover pan 34 may receive oil percolating upwardfrom a plurality of wellhead cover pans 35, as illustrated in FIG. 4, inwhich centrally peaked gutter 41 delivers tributary oil from any roofportion 34 or 35 to the central roof receiving chamber 43.

In the embodiment illustrated in FIG. 2, roof 31 has a levelconfiguration over wellhead structure B. The forward, near and lateraledges of the top 32 of each portion of roof 31, specifically manifoldcover pan,34 and wellhead cover pan 35, are provided with dependent sidecurtains 33. In this form of roof, each portion 34 and 35 of the roofserves as a collecting module for rising fugitive oil fluids. Themanifold cover pan 34 largely collects oil fluids rising from themanifold portion of the submerged well structure B, and the wellheadcover pan 34 largely collects oil fluids rising from the wellhead ofwellhead structure B. In either embodiment, that of FIG. 1 or FIG. 2,the manifold cover pan 34 and the wellhead cover pan 35 of the roof 31cooperatively serve to capture oil escaping from well structure 8 and toconfine the oil underwater above an oil-water interface 44 bounded by atleast one of them.

Oil confined under roof 31 above oil-water interface 44 is removed fromits underwater confinement and discharged into well structure B free ofsea water by means of a fluid conduit 45 connecting roof 31 and wellstructure B. Referring to FIG. 1, fluid conduit 45 has an inlet 46opening into the receiving chamber 43 of roof 31 and an outlet 47opening into a production line of well structure B, suitably down-holeproduction tubing, wellhead production lines 12, 13, or, as illustrated,into header portion 37 of production manifold 14. Admission into inlet46 of oil above interface 44 is controlled by a normally closed inletvalve 48 operatively associated with an oil-water interface leveldetecting device 49 which opens inlet valve 48 when the oil-waterinterface 44 reaches a predetermined minimum level below inlet 46 andcloses inlet valve 48 when interface 44 climbs to a selected level belowinlet 47 with drainage of oil into fluid conduit 45. Suitably, interfacelevel detecting device 49 may include a relay for electrically actuatingvalve 48 on closure of the relay by downward movement of float 50 onpivot arm 51 to the predetermined minimum location within side curtains33 of roof 31 below inlet 46. (Other oil-water interface level detectingdevices suitably include solid state electrical micro switches,capacitance probe-type oil detectors, magnetic permeability switches andthe like, as known to the art, although the float actuated mechanicallink is preferred for its long service life and reliability.) When inlet46 is opened, oil above interface 44 is driven into fluid conduit 45 bythe heavier sea water if line pressure in production manifold 14 is lessthan the hydrostatic pressure of the water at the level of theunderwater structure. If line pressure is greater than the hydrostaticpressure at that level, oil from the production manifold may backflowthrough fluid conduit 45, driving interface level 44 down withinreceiving chamber 43 to a predetermined maximum level to which interfacelevel detecting device 49 responds, as by closure of a second stagerelay, and engages circuitry leading to production control unit 24 toshut in production from well structure B. Response of interface leveldetecting device 49 to attainment of the predetermined maximum level mayalso engage circuitry which may be provided for electrical connection toan indicator installed at a remote accessible location to signifyaccumulation under roof 31 of a predetermined maximum volume of oilabove the predetermined maximum level. Alternatively, as illustrated inFIG. 1, a capacitance probe 52 or other level detecting means may beseparately installed in the lower portion of the receiving chamber 43,instead of being integrated with the structure of the device 49detecting the predetermined minimum level, for connection to electricalcircuitry leading to a remote indicator and/or operative connection toproduction control unit 24. A check valve 53 may suitably be provided influid conduit 45 to prevent backflow into chamber 43 of oil fromproduction manifold 14. If so, when inlet 46 is opened on attainment ofthe predetermined minimum volume and forward flow through fluid conduit45 is prevented by a higher pressure in the production line, wellstructure 8 will be shut in by continued collection of fugitive oil byroof 31 if the predetermined maximum volume interface level is attained.

Referring to FIG. 2, a preferred construction of fluid conduit 45 isillustrated in which outlet 47 is normally closed by outlet valve 54. Inthe modular construction of roof 31 in the embodiment depicted in FIG.2, fluid conduit 45 has dual inlets 55, 56 opening respectively into theoil confining areas of wellhead cover pan 35 and manifold cover pan 34.Fluid conduit inlets 55 and 56 are normally closed, respectively, byinlet valves 57 and 58. Each inlet valve 57, 58 operates independentlyof the other inlet valve to admit oil above the interface level,respectively, of wellhead cover pan 35 and manifold cover pan 34 intofluid conduit 45. As best seen in FIG. 5, the inlet valves (for example,inlet valve 58) are directly operated by float controlled linkagecomprising a pivot arm 59 which moves according to the disposition of aterminally attached float 60, float 60 following the level of theoil-water interface within the confines of roof 31. As float 60 descendswith a falling interface level 44, pivot arm 59 rotates shaft 61. Wheninterface 44 reaches a predetermined minimum level, shaft 61 opens theinlet valve. Shaft 61 simultaneously closes a relay in switch 62 whichis provided for electrical connection to an indicator at a remoteaccessible location to actuate that indicav tor, signaling attainment byinterface 44 of the predetermined minimum location below inlet 56.Responsive to that signal, an operator at the remote accessible sitecompares the pressure in the production lines of the wellhead structureB, for example, in manifold 14, and ifthe production line pressure doesnot exceed hydrostatic pressure at the level of well structure B, theoperator engages circuitry in production control unit 24 throughpower-signal cable 25 to open valve 54 in fluid conduit 45, therebypermitting discharge from fluid conduit 45 through outlet 47 intoproduction manifold 14 of oil fluids admitted to fluid conduit 45 on theopening of the particular inlet valve 57 or 58. Elevation of float 60 toa selected higher level between the predetermined minimum level andinlet 55 or 56 turns shaft 61 to open the relay and close the particularinlet valve 57 or 58, preventing sea water from entering fluid conduit45. A check valve 53 may be provided, as in the embodiment of FIG. 1, toprevent back-flow of oil into the oil confinement area under roof 31 inthe event that a surge of production line pressure exceeds theenvironmental hydrostatic pressure. In the arrangement depicted in FIG.2, if the pressure in the production lines exceeds the local hydrostaticpressure when inlet valve 58 opens, switch 62 being actuated to signifythat event to a remote operator, the remote operator will not openoutlet valve 54, and oil fluids will continue to accumulate within theconfines of the portion 34 or 35 of roof 31 in which the inlet valve isopened. If oil accumulates to a predetermined maximum level between thelower edges of side curtains 33 and the particular inlet 55 or 56, alevel sensing device will respond to engage circuitry leading toproduction control unit 24 to shut in production from the well structureB. The level sensing device may suitably be either integrallyincorporated in level detecting device 57, 58 or separately installed,such as capacitance probes 63 and 64 respectively located in the lowerconfining areas of wellhead cover pan 35 and manifold cover pan 34.

A more preferred construction of fluid conduit 45 is illustrated in FIG.6 which permits oil fluids to be discharged into the well structure whenproduction line pressure exceeds local hydrostatic pressure. Inaddition, FIG. 6 illustrates by dashed lines a construction that permitsdischarge of oil fluids from fluid conduit 45 into whichever one of aplurality of production lines of well structure B has a lower linepressure than the hydrostatic pressure at the level of the wellstructure. Referring to FIG. 6, fluid conduit 45, provided with anoutlet valve 54 as illustrated in FIG. 2, is further provided with abypass conduit 65 which bypasses outlet valve 54, entering fluid conduit45 ahead of outlet 47. A suitable submersible pump 66 is linked intobypass line 65. Check valves 67 and 68 are installed, respectively, inbypass line 65 between pump 66 and where line 65 re-enters fluid conduit45, and in fluid conduit 45 between outlet valve 54 and the entrance ofline 65 with fluid conduit 45. With this construction, when alerted bysignal that an inlet valve has opened admitting oil fluids into fluidconduit 45, a remote operator may discharge oil fluids from fluidconduit 45 into production manifold 14 without backflow, even throughline pressure in manifold 14 exceeds local hydrostatic pressure. Theoperator leaves valve 54 closed, and energizes pump 66 in line 65,pumping oil fluids in line 45 through bypass line 65 to the entrance ofline 65 into line 45 and thence into header 37 of manifold 14 throughoutlet 47. Check valves 67 and 68 prevent damage to pump 66 and outletvalve 54, respectively, from abnormally high pres sure surges in theproduction lines.

The preferred construction of FIG. 6 is further illustrated by dashedlines in which fluid conduit 45 is depicted as having a plurality ofoutlets 47 and 47' opening into a plurality of production manifolds 14,15 of well structure B. Structure depicted by the dashed linescorresponding to structure illustrated by the solid lines of FIG. 6 isidentically enumerated, but differentiated with superscript prime marks.In the arrangement shown by dashed lines, the operator, when signaledthat an inlet valve has opened, may poll the pressures of the variousproducing lines, and if the line pressure in any one of the plurality ofproduction lines is less than the hydrostatic pressure at well structurelevel, the operator may route the oil fluids in fluid conduit 45 to thatlesser pressure production line by actuating only the particular outletvalve controlling the outlet into that production line. For example, ifin FIG. 6 the pressure in manifold 15 is less than hydrostatic pressureat the level of well structure B and the pressure in manifold 14 exceedsthat hydrostatic pressure, outlet valve 54 is maintained closed andoutlet valve 54' is opened, permitting oil fluids in fluid conduit 45and 45' to be driven by gravity into the header of production manifold14 through outlet 47'. In combination with bypass line 65 and pump 66,the structure illustrated by dashed lines permits the operator to chosewhether to operate pump 66 or not, unles all producing line pressuresexceed local hydrostatic presure, in which case pump 66 is used if wellstructure B is not to be automatically shut-in.

For use as an underwater pump 66, a small triplex or a centrifugal pumpdriven by either a submersible electric motor or a submersible hydraulicmotor immersed in an oil-filled pressure balance container is suitable.Another suitable pump system is schematically depicted in FIG. 7, inwhich pressure in the production manifold header 37 exceeding thehydrostatic pressure of the water at the well structure level isutilized to create a Venturi eflect. Referring to FIG. 7, referencenumeral 37 indicates the manifold production header of well structure Bin FIGS. 1 and 2. A through flowline (TFL) service line 70 transmittingfluids from a remote production facility into wellhead by valvingapparatus familiar to the art is provided with a crossover line 71joining TFL line 70 with manifold production header 37. Crossover line71 con tains a constriction 72 which receives the outlet 47 of fluidconduit 45. Outlet 47 is normally closed by outlet valve 54 which isoperated by hydraulic lines leading to production control unit 24.Intermediate the takeoff of crossover line 71 from 'I'FL line 70 andconstriction 72, crossover line 71 is normally closed by crossover linevalve 73 controlled by hydraulic lines running from production controlunit 24. Flow into crossover line 71 of production fluids from TFL line70 and from crossover line 71 into manifold production header 37 ispermitted when crossover line valve 73 is opened by remote operationthrough production control unit 24. Flow of production fluids throughconstriction 72 in line 71 creates a pressure drop at constriction 72.Actuation of valve 54, opening the outlet of fluid conduit 45, creates asuction in fluid conduit 45 which draws oil above oil-water interface 44through fluid conduit 45 into crossover line 71 and thence intoproduction manifold header 37. Although not specifically illustrated inFIG. 6, it will be understood that the inlet 45 is guarded by an inletvalve as in FIGS. 1 and 2.

As hereinbefore stated, manifold cover pan 34 is aifixed over productionmanifolds l4, l5. Suitably, manifold cover pan 34 may be attached to itsmount prior to lowering of the well structure B on template 27 intoplace on ocean bottom 26.

Removable wellhead cover pan 35 is installed after well structure 8 andmanifold cover pan 34 are set in place on ocean bottom 26. In FIGS.8-12, the operation of structure of wellhead cover pan 35 coacting witha remotely operated running and retrieving tool for removably securingwellhead cover pan 35 above wellhead 10 is illustrated for theembodiment of wellhead cover pan 35 depicted in FIG. 1. Referringparticularly to FIGS. 8 and 9, wellhead cover pan 35 is pivotally hingedin its forward portion by means of a plurality of hinge pins seated inmounting rings 76 affixed to confronting sides of guide sleeves 77. 'Ihetop surface 32 of wellhead cover pan 35 mounts a crossbar 78 betweenupstanding ears secured to the rear of the center of wellhead cover pan35. A semicircular stop 80 is braced behind ears 79 at an acute anglewith top surface 32 by a brace 81.

Coacting with the structure of wellhead cover pan 35 is a running andretrieving tool indicated generally by reference numeral 82. Referringto FIG. 8, tool 82 includes a central tubular body or mandrel 83connected to a tubular running-in string 84, as by threaded attachmentof an upward box in mandrel 38 with a lower pin end of the running-instring 84. Referring to FIG. 9, the lower end of tubular mandrel 83 isconstituted as a tubular neck 85 tenninating in a piston head 86, whichattaches a plurality of dependent, normally extended, opposed springfingers 86. A latching sleeve 87 surrounds piston head 85 in a largerinner diameter lower portion of the sleeve and surrounds lower neck 84of tubular body 83 in a smaller inner diameter upper portion, whichincludes in its inner circumference a circular recess 88 housing asuitable seal ring or gasket 89, such as an O-ring. A circumferentialrecess 90 is provided in the outer circumference of piston head 85 tohouse a suitable seal ring or gasket 91. Sealing members 89 and 91together prevent leakage of fluid between tubular body 83 and latchingsleeve 87. Spring fingers 86 are provided with outside stops 92 whichlimit downward extension of latching sleeve 87 on neck 84 and pistonhead 85 of tubular body 83. Force giving rise to a downward extension oflatching sleeve 87 is imparted to sleeve 87 by a helical springencompassing neck 84 and compressed between outer shoulders 94 and 95,respectively, of tubular body 83 and latching sleeve 87. In fullextension on neck 84 and piston head 85, latching sleeve 87 defines anannular space 96 between its inner shoulders 97 and the upper innershoulders 98 of piston head 85. In operation, hydraulic fluid is pumpedthrough tubular passageway 99 into annular space 97 to retract latchingsleeve 87 on the circumference of piston head 85 against the compressiveforce of spring 93, thereby opening spring fingers 86 for closure aboutcrossbar 79 on wellhead cover pan 35. Hydraulic fluid is then withdrawnfrom annular space 97 in balanced measure against the force of spring 93so that latching sleeve 87 descends about piston head 85 until thedownward extension of its movement is limited by stops 92, therebyclosing and locking spring fingers 86 inwardly about crossbar 78 ofwellhead cover pan 35. As illustrated in FIG. 8, running-in string 84,when hoisted, permits the wellhead cover pan to rotate on pins 75mounted to guide sleeves 77 to produce a tilted attitude which reducesthe projected area of the wellhead cover pan such that, when thewellhead cover pan is run in by string 84 guided by guide sleeves 77running on guide wires 30 from guidepost 29a, the leading edge 38 of thewellhead cover pan 35 clears the rear edge 39 of fixed manifold coverpan 35. During descent, the tilted attitude of the wellhead cover pan ismaintained by abutment of semicircular stop 80 against latching sleeves87 of tool 82, as depicted by FIGS. 7 and 10. Descent of wellhead coverpan 35 is stopped when guide sleeve 77 impinges upon limit ring 100attached to guidepost 29a. Further downward movement of running-instring 84 rotates wellhead cover pan 35 about the axis of hinge pins 75,semicircular stop 80 disengaging latching sleeve 87, until wellheadcover pan 35 is deposited on a cross member 101 spanning rear guidepost29b. Tool 82 is then released from crossbar 78 of wellhead cover pan 35by pumping hydraulic fluid into annular space 97 to retract latchingsleeve 87, permitting spring fingers 86 to expand outwardly to releasethe crossbar. Running-in string 84 is then retrieved to the surface. Asreference to FIG. 12 taken with FIG. 4 illustrates, wellhead cover pans35 may be so installed in back-to-back multi-wellhead templatestructures.

Alternative structure of wellhead cover pan 35 for coacting with runningand retrieving tool 82 for removably securing wellhead cover pan 35above wellhead in the embodiment of wellhead cover pan 35 depicted inFIG. 1 is illustrated in FIGS. 13(a)l3(c) taken with FIGS. 14 and 15. Inthis form, wellhead cover pan 35 is run in without the necessity ofusing a conventional guidepost system. As in the embodiment discussed inconnection with FIGS. 8-12, wellhead cover pan 35 is provided with anoff-center crossbar 78 secured to top surface 32 by a pair of cars 79.Attachment of the running tool to off-center crossbar 78 as shown inFIG. 13(a) causes the forward edge 38 of the cover 35 to rotate down toa tilted attitude reducing the projected area of cover 35 so that, whenlowered, it clears the rear edge 39 of the fixed manifold cover pan 34.Referring to FIG. 14 taken with FIG. 13(a), the undersurface of top 32of wellhead cover pan 35 is provided with a pair of notched ribs 102longitudinal and inboard of lateral side curtains 33. Each of the ribs102 is tapered to define a notch 103 between a leading anterior portion104 and a trailing posterior portion 105. As the wellhead cover pan 35is lowered, the leading portion 104 contacts a cross member 106 rovidedin structure erected on template 27 (FIG. 13(a)). Leading portion 104then slides forward on its edge until it is stopped by notch 103. Aslowering continues, wellhead cover pan 35 rotates about notch 103 sothat the forward edge 38 of the cover 35 is under the fixed manifoldcover pan 34, as depicted in FIG. 13(0). In this position, the rear endof top surface 32 rests on a cross support member of framework ontemplate 27. As depicted in FIG. 15, notch 103 may include a recesswithin rib 102 for hooking rib 102 on cross member 106 to preventslippage. Wellhead cover pan 35 may be run in using an external guidancesystem other than the conventional guidepost system.

Installation of the wellhead cover pan 35 depicted for the embodiment ofFIG. 2 proceeds according to conventional running and retrieving ofguide sleeves on guideposts. Referring to FIG. 2, running-in andretrieving tool 82 may coact with a center mounted crossbar 78' mountedto top surface 32 of cover 35 on upstanding ears 79'. Referring to FIG.16, side curtains 33 are secured, as by wellments, to guide sleeves 11070 which guide the lowering of wellhead cover pan 35 by following guidewires 30 onto guide posts 34, which are fitted with limit stops 111. Inthe embodiment of FIG. 2, as in the embodiments of FIG. I, the fluidconduit 45 is mounted with equipment installed on template 27 whentemplate 27 is set on ocean bottom 26.

After installation of underwater pollution control device A oversubmerged well structure B, fluid conduit 45 is purged of sea water byremotely actuating, in the embodiment of FIG. 1, inlet valve 48, and inthe embodiment of FIG. 2, outlet valve 54 and inlet valves 57, 58,momentarily to open those valves when pressure in the production linesystem exceeds hydrostatic pressure at the level of the well structure8, production fluids from the production lines forcing sea water fromfluid conduit 45. fire cooperative action of oil-water interface leveldetecting device 49 and the inlet valve (3) of the particular structurethereafter prevent entrance of sea water into fluid conduit 45.

Having fully and particularly described apparatus which accomplish thehereinbefore stated objects of this invention, and having disclosed thebest modes contemplated for the purposes of this invention, I claim anddesire to secure by Letters Patent:

1. An underwater pollution control apparatus for a submerged wellstructure comprising:

a. confining means for confining fugitive oil from said well structureunderwater above an oil-water interface, said confining means extendingover said well structure, and

b. responsive means responsive to the level of said interface forshutting in production from said well structure when said interface isat a predetermined maximum level within said confining means.

2. The underwater pollution control apparatus of claim 1 furthercomprising means for electrical connection to an indicator at a remoteaccessible location for actuating said indicator when said interface isat said predetermined maximum oil level.

3. An underwater pollution control apparatus for a submerged wellstructure, comprising:

a. confining means for confining fugitive oil from said well structureunderwater above an oil-water interface, said confining means extendingover said well structure, and

b. oil removing means having an inlet opening into said confining meansabove said oil-water interface and an outlet opening into said wellstructure for removing said oil from said confining means anddischarging it into said well structure free of sea water, said oilremoving means including means responsive to the level of said oil-waterinterface for admitting oil through said outlet where said interface isat a predetermined minimum level below said inlet and for closing saidinlet when said interface is at a selected level below said inlet higherthan said predetermined minimum level.

4. The underwater pollution control apparatus of claim 3, furthercomprising pump means operatively associated with said fluid conduitmeans for pumping oil from said fluid conduit means into said wellstructure.

5. The underwater pollution control apparatus of claim 3 furthercomprising responsive means responsive to the level of said interfacefor shutting in production from said well structure when said interfaceis at a predetermined maximum level within said confining means belowsaid inlet.

6. The underwater pollution control apparatus of claim 5 in which saidoil removing means includes means for preventing backflow through saidinlet of oil in said oil removing means.

7. The underwater pollution control apparatus of claim 5, furthercomprising pump means operatively associated with said fluid conduitmeans for pumping oil from said fluid conduit means into said wellstructure.

8. The underwater pollution control apparatus of claim 5 furthercomprising means for electrical connection to an indicator at a remoteaccessible location for actuating said indicator when said interface isat a predetermined minimum location below said inlet.

9. The underwater pollution control apparatus of claim 8, furthercomprising pump means operatively associated with said fluid conduitmeats for pumping oil from said fluid confixed manifold cover pan 34 andlowered with the production duit means into said well structure.

10. The underwater pollution control apparatus of claim 8 in which saidoil removing means includes means for controlling the discharge throughsaid outlet into said well structure of oil from said oil removingmeans.

11. The underwater pollution control apparatus of claim 10 furthercomprising regulative means operatively associated with said fluidconduit means for preventing backflow through said inlet of oil in saidfluid conduit means.

12. The underwater pollution control apparatus of claim 1 1, furthercomprising pump means operatively associated with said fluid conduitmeans for pumping oil from said fluid conduit means into said wellstructure.

13. An underwater pollution control apparatus extended over a submergedwell structure including a wellhead and at least one productionmanifold, comprising:

a. a roof having side curtains, including a manifold portion of saidroof which is affixed to said well structure above said manifold, and awellhead portion of said roof which is removably secured over saidwellhead and has means for coacting with a running-in device forremovably installing and retrieving said wellhead portion, said portionsof said roof being operatively associated to confine above an oil-waterinterface bounded by at least one of them essentially all oil escapingfrom said submerged well structure;

b. fluid conduit means having at least one outlet opening into said wellstructure and at least one inlet opening into at least one of saidportions of said roof for conducting oil from above said interface intosaid well structure;

c. level detecting means arranged under at least one of said portions ofsaid roof for detecting when said interface is at a predetermined level;

d. an inlet control means operatively associated with said fluid conduitmeans and operatively connected with said level detecting means foradmitting oil through said inlet into said fluid conduit means inresponse to a detection by said level detecting means that saidinterface is at a predetermined minimum level below said inlet and forclosing said inlet in response to a detection by said level detectingdevice that said interface is at a selected level below said inlet thatis higher than said predetermined minimum level; and

e. means operatively connected to said level detecn'ng means forshutting in production from said well structure in response to adetection by said level detecting means that said interface is at apredetermined maximum level below said inlet within the confines of saidroof.

14. The underwater pollution control apparatus of claim 13 furthercomprising regulative means operatively associated with said fluidconduit means for preventing backflow through said inlet of oil in saidfluid conduit means.

15. The underwater pollution control apparatus of claim 13 furthercomprising pump means operatively associated with said fluid conduitmeans for pumping oil from said fluid conduit means into said wellstructure.

16. The underwater pollution control apparatus of claim 13 furthercomprising means for electrical connection to an indicator at a remoteaccessible location for actuating said indicator in response to adetection by said level detecting means that said interface is at saidpredetermined maximum level.

17. The underwater pollution control apparatus of claim 13 furthercomprising means for electrical connection to an indicator at a remoteaccessible location for actuating said indicator in response to adetection by said level detecting means that said interface is at saidpredetermined minimum level.

18. The underwater pollution control apparatus of claim 17 furthercomprising pump means operatively associated with 5 said fluid conduitmeans for pumping oil from said fluid conduit means into said wellstructure.

19. The underwater pollution control apparatus of claim 17 furthercomprising an outlet control means operatively as sociated with saidfluid conduit means which controls the admission of oil from said fluidconduit means into said well structure through said outlet.

20. The underwater pollution control apparatus of claim 19 furthercomprising regulative means operatively associated with said fluidconduit means for preventing backflow through said inlet of oil in saidfluid conduit means.

2!. The underwater pollution control apparatus of claim 19 furthercomprising pump means operatively associated with said fluid conduitmeans for pumping oil from said fluid conduit means into said wellstructure and regulative means operatively associated with said fluidconduit means for preventing backflow through said inlet of oil in saidfluid conduit means.

22. The underwater pollution control apparatus of claim 13 in which saidroof is upwardly inclined from said portion over said wellhead to saidportion over said manifold whereby oil confined under the portion ofsaid roof over said well head passes by displacement of water to theportion of said roof over said manifold.

23. The underwater pollution control apparatus of claim 22 in which saidportion of said roof above said manifold includes accumulating means foraccumulating oil above an oil-water interface.

24. A method of recovering oil emanating into subsurface waters from asubmerged well structure and preventing oil 3 5 pollution of surfacewaters, comprising:

confining fugitive oil from said submerged well structure underwaterimmediately above said structure, accumulating the oil until apredetermined minimum of volume is obtained, and then discharging atleast a portion of the accumulated oil into said submerged wellstructure while preventing entrance of sea water into such structure.

25. The method of claim 24 further comprising:

accumulating confined fugitive oil not discharged into said submergedwell structure until a predetermined maximum volume is attained, andthen shutting in production from said submerged well structure inresponse to the attainment of said predetermined maximum volume.

26. The method of claim 24 further comprising signaling a remoteaccessible location of the accumulation of said predetermined minimumvolume of fugitive oil.

27. The method of claim 26 in which said oil is discharged into saidsubmerged well structure on instruction from said 55 remote accessiblelocation.

28. A method for preventing pollution of surface waters by oil from asubmerged well structure, comprising:

confining fugitive oil from said well stnicture underwater immediatelyabove said structure,

accumulating said oil until a predetermined maximum volume is obtained,and then shutting in production from said submerged well structure inresponse to the attainment of said predetermined maximum volume.

65 e e e e e

1. An underwater pollution control apparatus for a submerged wellstructure comprising: a. confining means for confining fugitive oil fromsaid well structure underwater above an oil-water interface, saidconfining means extending over said well structure, and b. responsivemeans responsive to the level of said interface for shutting inproduction from said well structure when said interface is at apredetermined maximum level within said confining means.
 2. Theunderwater pollution control apparatus of claim 1 further comprisingmeans for electrical connection to an indicator at a remote accessiblelocation for actuating said indicator when said interface is at saidpredetermined maximum oil level.
 3. An underwater pollution controlapparatus for a submerged well structure, comprising: a. confining meansfor confining fugitive oil from said well structure underwater above anoil-water interface, said confining means extending over said wellstructure, and b. oil removing means having an inlet opening into saidconfining means above said oil-water interface and an outlet openinginto said well structure for removing said oil from said confining meansand discharging it into said well structure free of sea water, said oilremoving means including means responsive to the level of said oil-waterinterface for admitting oil through said outlet where said interface isat a predetermined minimum level below said inlet and for closing saidinlet when said interface is at a selected level below said inlet higherthan said predetermined minimum level.
 4. The underwater pollutioncontrol apparatus of claim 3, further comprising pump means operativelyassociated with said fluid conduit means for pumping oil from said fluidconduit means into said well structure.
 5. The underwater pollutioncontrol apparatus of claim 3 further comprising responsive meansresponsive to the level of said interface for shutting in productionfrom said well structure when said interface is at a predeterminedmaximum level within said confining means below said inlet.
 6. Theunderwater pollution control apparatus of claim 5 in which said oilremoving means includes means for preventing backflow through said inletof oil in said oil removing means.
 7. The underwater pollution controlapparatus of claim 5, further comprising pump means operativelyassociated with said fluid conduit means for pumping oil from said fluidconduit means into said well structure.
 8. The underwater pollutioncontrol apparatus of claim 5 further comprising means for electricalconnection to an indicator at a remote accessible location for actuatingsaid indicator when said interface is at a predetermined minimumlocation below said inlet.
 9. The underwater pollution control apparatusof claim 8, further comprising pump means operatively associated withsaid fluid conduit means for pumping oil from said fluid conduit meansinto said well structure.
 10. The underwater pollution control apparatusof claim 8 in which said oil removing means includes means forcontrolling the discharge through said outlet into said well structureof oil from said oil removing means.
 11. The underwater pollutioncontrol apparatus of claim 10 further comprising regulative meansoperatively associated with said fluid conduit means for preventingbackflow through said inlet of oil in said fluid conduit means.
 12. Theunderwater pollution control apparatus of claim 11, further comprisingpump means operatively associated with said fluid conduit means forpumping oil from said fluid conduit means into said well structure. 13.An underwater pollution control apparatus extended over a submerged wellstructure including a wellhead and at least one production manifold,comprising: a. a roof having side curtains, including a manifold portionof said roof which is affixed to said well structure above saidmanifold, and a wellhead portion of said roof which is removably securedover said wellhead and has means for coacting with a running-in devicefor removably installing and retrieving said wellhead portion, saidportions of said roof being operatively associated to confine above anoil-water interface bounded by at least one of them essentially all oilescaping from said submerged well structure; b. fluid conduit meanshaving at least one outlet opening into said well structure and at leastone inlet opening into at least one of said portions of said roof forconducting oil from above said interface into said well structure; c.level detecting means arranged under at least one of said portions ofsaid roof for detecting when said interface is at a predetermined level;d. an inlet control means operatively associated with said fluid conduitmeans and operatively connected with said level detecting means foradmitting oil through said inlet into said fluid conduit means inresponse to a detection by said level detecting means that saidinterface is at a predetermined minimum level below said inlet and forclosing said inlet in response to a detection by said level detectingdevice that said interface is at a selected level below said inlet thatis higher than said predetermined minimum level; and e. meansoperatively connected to said level detecting means for shutting inproduction from said well structure in response to a detection by saidlevel detecting means that said interface is at a predetermined maximumlevel below said inlet within the confines of said roof.
 14. Theunderwater pollution control apparatus of claim 13 further comprisingregulative means operatively associated with said fluid conduit meansfor preventing backflow through said inlet of oil in said fluid conduitmeans.
 15. The underwater pollution control apparatus of claim 13further comprising pump means operatively associated with said fluidconduit means for pumping oil from said fluid conduit means into saidwell structure.
 16. The underwater pollution control apparatus of claim13 further comprising means for electrical connection to an indicator ata remote accessible location for actuating said indicator in response toa detection by said level detecting means that said interface is at saidpredetermined maximum level.
 17. The underwAter pollution controlapparatus of claim 13 further comprising means for electrical connectionto an indicator at a remote accessible location for actuating saidindicator in response to a detection by said level detecting means thatsaid interface is at said predetermined minimum level.
 18. Theunderwater pollution control apparatus of claim 17 further comprisingpump means operatively associated with said fluid conduit means forpumping oil from said fluid conduit means into said well structure. 19.The underwater pollution control apparatus of claim 17 furthercomprising an outlet control means operatively associated with saidfluid conduit means which controls the admission of oil from said fluidconduit means into said well structure through said outlet.
 20. Theunderwater pollution control apparatus of claim 19 further comprisingregulative means operatively associated with said fluid conduit meansfor preventing backflow through said inlet of oil in said fluid conduitmeans.
 21. The underwater pollution control apparatus of claim 19further comprising pump means operatively associated with said fluidconduit means for pumping oil from said fluid conduit means into saidwell structure and regulative means operatively associated with saidfluid conduit means for preventing backflow through said inlet of oil insaid fluid conduit means.
 22. The underwater pollution control apparatusof claim 13 in which said roof is upwardly inclined from said portionover said wellhead to said portion over said manifold whereby oilconfined under the portion of said roof over said well head passes bydisplacement of water to the portion of said roof over said manifold.23. The underwater pollution control apparatus of claim 22 in which saidportion of said roof above said manifold includes accumulating means foraccumulating oil above an oil-water interface.
 24. A method ofrecovering oil emanating into subsurface waters from a submerged wellstructure and preventing oil pollution of surface waters, comprising:confining fugitive oil from said submerged well structure underwaterimmediately above said structure, accumulating the oil until apredetermined minimum of volume is obtained, and then discharging atleast a portion of the accumulated oil into said submerged wellstructure while preventing entrance of sea water into such structure.25. The method of claim 24 further comprising: accumulating confinedfugitive oil not discharged into said submerged well structure until apredetermined maximum volume is attained, and then shutting inproduction from said submerged well structure in response to theattainment of said predetermined maximum volume.
 26. The method of claim24 further comprising signaling a remote accessible location of theaccumulation of said predetermined minimum volume of fugitive oil. 27.The method of claim 26 in which said oil is discharged into saidsubmerged well structure on instruction from said remote accessiblelocation.
 28. A method for preventing pollution of surface waters by oilfrom a submerged well structure, comprising: confining fugitive oil fromsaid well structure underwater immediately above said structure,accumulating said oil until a predetermined maximum volume is obtained,and then shutting in production from said submerged well structure inresponse to the attainment of said predetermined maximum volume.